scilearner

1. Ok in the plasmid we used the ECOR1 to create sticky ends. Now my question is when we add DNA ligase, why don't these ends stick back again. How are we able to add new DNA piece in between. Basically what I'm saying is when ECOR 1 creates sticky ends in plamids, why do they separate the plamid, don't the sticky ends stick back together.

2. Also why can't DNA ligase bind the blunt ends, can't it fix the phosphodiester bond there.

Thanks

Hello everyone,

1. Restriction enzymes cut only sugar phospahte bonds right. So in the formation of sticky bonds for example in BamHl, how does the hydrogen bonds between the molecules break. When sugar phophate bonds on each strand break, does it pull on the free side dissociating the hydrogen bonds. Can these pieces stick back easily again or do they need a ligase?

2. Can restriction enzymes cut single stranded DNA?

3. Also how do these detect specific sequences of DNA. Do they have some complementary area that binds with the specific region.

Thanks

Hello everyone,

I have a quick question, let's say there is a L1 dermatome, which is a large area. Now my question is does L1 nerve divide into many branches to supply this area, also do these branches carry only sensory nerves?

Thanks

Hello everyone,

Ok I know this goes away from stoma, so why do myelinated nerves use only this type but not antidromic.Thanks

Hello everyone,

I don't understand how depolarisation jumps when axons are myelinated. Ok myelin is an insulator so in that section no current passes through. But how does that make the current jump, when current reached myelin wouldn't it be inhibited, why does it still travel. Also what do they mean by developing current sinks at nodes of ranvier. Thanks

Hello everyone,

Quick question. When diaphragm contracts, it must contract all the abdominal organs like liver and stomach. When this happens constantly wouldn't it damage these organs. Thanks

Hello everyone,

Ok I'm confused again (surprise). Let's say there is a semipermeable membrane and on one side there was 100 percent water. On the other side there are solutes mixed with water. Now water should move from high to low, but where is the water from 100 percent side going to move into. There are no gaps on other side, other side is full of water mixed with solutes. So why does it diffuse. Thanks

Hello everyone,

I know nerve fibres inside brain are not covered by perineurium etc like Peripheral nervous system. Are they still covered with connective tissue, support cells, myelin etc. I mean inside the brain , a collection of nerve fibres, how are they held together with no connective tissue. I don't have much knowledge about brain. Thanks

Thanks Cypress now I understand

Now I'm confused. Ok let's say there is a container with oxygen (Pa=100mmHg) and carbon dioxide (p=20mmHg) . Now total pressure is 120 mmHg. So if I remove carbon dioxide, the total pressure in the chamber becomes 100 mmHg. Is that right?

Ok but inside the lung there is oxygen and carbon dioxide. If I breathe fast and remove carbon dioxide, the partial pressure of oxygen increases? Why is that? When carbon dioxide is rapidly removed, does more oxygen from atmosphere enter the lung. Is that the reason. Please answer both questions. Thanks

Hello everyone,

This is what I'm thinking. Tell me if this is wrong

Blood cerebrospinal fluid barrier: Blood goes through ependymal cells, which filter it, and create CSF that circulates in brain.

Blood brain barrier: This create CSF is further protected from incoming blood vessels, by this barrier allowing only some to diffuse.

Also what is tela choroidea, I know it is two layered fold of pia matter but how is helping to form chorodal plexus. Do blood vessel come from it?

Thanks :smile:

Thanks both of you. Nice explanations

Hello everyone,

I'm confused with partial pressure of a gas.

Wiki: In a mixture of ideal gases, each gas has a partial pressure which is the pressure which the gas would have if it alone occupied the volume.

Now in a container if I have oxygen and carbon dioxide. If I remove carbon dioxide, shouldn't the oxygen occupy more space and its pressure decrease. So how can you call partial pressure of a gas pressure which the gas would have if it alone occupied the volume. Thanks

But secondary spermoctye have 23 double structured chromosomes. That means potentially 46 chromosomes.

Hello everyone,

Ok I know it has 23 chromosomes. But they are double structured chromosomes, so can you still call them haploid. Also spermatids, can you call them haploid cells. You can't right because they haven't matured.

Hello everyone,

Now at higher lung volumes intrapleural pressure must be positive. But according to the graph as inspiration increases intrapleural pressure is becoming more negative?

Please help!! Thanks

It's like escaping reality and creating a virtual world. Customers would have a much more relaxed mind and are more likely to purchase goods. However for me the bigger question is how on earth do people spend like 6 hours shopping . There are so many better things to do in that time

Hello everyone,

There was a simple question given, where there was a bee sting on a guy and the question asked was what is the antibody involved. The answer is IgE. Now my question is when there is bee sting for the first time, why do we called it an allergic reaction. I mean for an allergy to occur don't we have to be exposed to the antigen second time, so IgE attached to Mast cells will release histamine 2nd time. Also why aren't other antibodies like IgA ect not involed in a bee sting. Thanks

Hello everyone,

In fetal circulation most blood from inferior vena cavae go to left atrium via foramen ovale. This is not the case for superior vena cavae. But both drain into right atrium, so how is their a difference? Thanks.

Hello,

"Cereals provide 25-60 % of total protein intake"

Don't be harsh on me but I'm bit confused by this sentence. Does this mean that if your total protein intake is X. Eating like 100 g of cereals provide 25-60% of that. Thanks So if I eat more can I make it 100 percent.

Hello everyone,

I'm slightly confused here. After ovulation, progesterone increases markedly. Now progesterone is also used as a contraceptive for creating a hostile environment for fertilisation and not allowing sperm to enter. So after ovulation how does fertilisation occur normally, if progesterone increases right after that. I see that it takes like 5 days for progesterone to peak. So does fertilisation have to occur before progesterone increases a lot. Also after fertilisation, doesn't the effects of progesterone cause any problems to the fertilized egg. Thanks

Hello everyone,

I can understand how liver failure can cause jaundice, but not vise versa. Please help. Thanks

Hello guys I just want to know why is that when 2 flows are parallel and opposite to each other, a concentration gradient is maintained always.

Hello everyone,

I searched the net but I don't understand the difference.

BLO0D FLOW ---------------------------------->

0% ........................................… saturation

0% ........................................… saturation

WATER FLOW <-------------------------------

Countercurrent

BLO0D FLOW ---------------------------------->

0% ........................................… saturation

100%..................................… saturation

WATER FLOW --------------------------------->

Concurrent

I understand how equilibrium would be reached in concurrent but I don't understand how counter current maintains a concentration gradient. Please explain in simple language. Also if you can explain the above diagrams, I got it from net I don't understand them much. Thanks

Hello everyone,

What I just read is for type 1 diabetes mellitus, it requires an environmental factor (eg virus) and genetic determinant that allows the B cells to be detected as non self. Now I'm not very familiar with autoimmune diseases. My question is why does a virus have to come and trigger the autoimmune destruction of B cells. If B cells are alreadly genetically non self, shouldn't the body start attacking them without a stimulus? Thank you